The present invention relates to circuits and methods for generating sequential, multiple electrical impulses to actuate, fire or initiate a plurality of output devices. The invention permits the actuating, firing, and initiating of the multiple output devices at predetermined times.
A variety of single use mechanical devices are actuated by pyrotechnic loaded cartridges. These types of cartridges are called impulse cartridges since they provide a single impulse of work to actuate the device. Examples of these impulse actuated devices include cable cutters, piston actuators, vehicle safety systems, and military aircraft countermeasure devices having release systems and launchers which dispense chaff and flare countermeasure devices to evade attacking missiles.
Many of these devices require a cartridge with a single output which is activated by a pulse of electrical current applied to the device through a conducting pair of wires. In some applications, the actuating device requires two or more pyrotechnic outputs which are time separated. These multi-output cartridges typically require a controller or timing device external to the cartridge, and multiple pairs of wires leading to the cartridge in order to initiate the events separately and with the proper time separation.
For example, U.S. Pat. No. 4,313,379 to Wallace, "Voltage-Coded Multiple Payload Cartridge" improved upon this arrangement for multi-output cartridges. This patent allows a second output to be fired through a single wire pair by using a voltage sensitive diode (a zener diode) to distinguish the first from the second electrical pulse, and directing the electrical energy first to the first output and next to the second. The timing function for this invention is performed in a separate device installed external to the impulse cartridge. The particular application this invention focused upon was the dispensing of countermeasures to protect aircraft from attacking missiles.